Chlamydia pneumoniae growth inhibition in human monocytic THP-1 cells and human epithelial HEp-2 cells by a novel phenoxazine derivative

Abstract

In this study the effects of 2-amino-phenoxazine-3-one (phenoxazine derivate, Phx-3) on Chlamydia (Chlamydophila) pneumoniae growth in human monocytic THP-1 cells as well as human epithelial HEp-2 cells were examined. Cells were infected with bacteria at an m.o.i. of 10 by centrifugation. After washing to remove any remaining bacteria, the cells were incubated with or without Phx-3 in the presence or absence of tryptophan for 72 h. The bacteria in cells were assessed by staining of chlamydial inclusions with FITC-labelled anti-chlamydial antibody, electron microscopic analysis, real-time RT-PCR specific for C. pneumoniae 16S rRNA and propagation on HEp-2 cells. Treatment with Phx-3 significantly inhibited growth of C. pneumoniae in THP-1 and HEp-2 cells. A decrease in the number of bacterial 16S rRNA transcripts was also confirmed in both cell lines by real-time RT-PCR. Electron microscopic studies revealed that treatment with Phx-3 induces bacterial destruction in most of the inclusion bodies in these cells. Addition of tryptophan to the culture slightly blocked the growth inhibition of C. pneumoniae by Phx-3. The reagents did not show any cytotoxicity to the cells at the concentrations used. The results suggest that Phx-3 inhibits C. pneumoniae replication in human monocytic cells as well as epithelial cells, partially depending on the tryptophanmetabolic pathway of host cells. Thus, Phx-3 might be a useful compound for controlling C. pneumoniae growth in cells and may be an alternative conventional therapy.

Differential effects of Chlamydia pneumoniae infection on cytokine levels in human T lymphocyte- and monocyte-derived cell cultures

“…Cytokine levels in Cp-infected THP-1 cells THP-1 cells, a monocyte/macrophage cell line, are commonly used as a model for Chlamydia infection in phagocytic cells (Uruma et al, 2005;Yamaguchi et al, 2002b). Primarily, TNFa is produced by these cells in response to intracellular infection such as with Chlamydia.…”

The Role of Chlamydia and Chlamydophila Infections in Reactive Arthritis

“…Total bacterial RNA was extracted from cultures and specimens using RNeasy Mini Kit (Qiagen) according to the manufacturer's instructions for bacterial cells. The presence of C. pneumoniae and C. trachomatis were assessed by RT-PCR with primers specific for 16S rRNA, respectively (13,14). Serum was analyzed for antibodies to C. pneumoniae and C. trachomatis.…”

Novel Parachlamydia acanthamoebae Quantification Method Based on Coculture with Amoebae

“…For transmission electron microscopy (TEM), cells were immersed in a fixative containing 3% glutaraldehyde in 0.1 M phosphate-buffered saline, pH 7.4, for 24 h at 4°C. After a brief wash with phosphate-buffered saline, they were processed for alcohol dehydration and embedding in Epon 813, as described previously (64). Ultrathin sections of cells were stained with lead citrate and uranium acetate before being viewed by electron microscopy.…”